/Engine/Source/Developer/BSPUtils/Public/BSPOps.h
Duplicates the specified brush and makes it into a CSG-able level brush.
The new brush, or NULL if the original was empty.
static void csgCopyBrush ( [ABrush](API\Runtime\Engine\Engine\ABrush) * Dest, [ABrush](API\Runtime\Engine\Engine\ABrush) * Src, uint32 PolyFlags, EObjectFlags ResFlags, bool bNeedsPrep, bool bCopyPosRotScale, bool bAllowEmpty )